EEF-CVE-2026-82685 CVE-2026-82685 GHSA-g636-26vf-2w63
Confirmation token accepted on any record in AshAuthentication
- Severity
- 0.0 / 10
- Unknown · CVSS 4.0
- Exploit chance (EPSS)
- 0.66%
- Chance of exploitation in the next 30 days. Higher than 51.79% of scored vulnerabilities.
- Known exploited
- No
- Not in CISA's catalog
- Weakness
- CWE-639 Authorization Bypass Through User-Controlled Key
- Fix
5.0.0-rc.14- Upgrade ash_authentication to this version or later
Description
Summary
Authorization Bypass Through User-Controlled Key vulnerability in team-alembic AshAuthentication allows an authenticated attacker to overwrite and confirm another user's email address, and so take over that account. A confirmation token issued to one user is accepted on any other user's record.
AshAuthentication.AddOn.Confirmation.ConfirmChange verifies the token's signature and its act claim, then applies the changes stored against that token to whichever record the changeset targets, never comparing the sub claim against changeset.data. An attacker who registers an account and changes their own email replays the resulting token against a victim's record id, writing in their own address with force_change_attributes/2 and stamping confirmed_at, after which an ordinary password reset yields the account. The library's own confirmation flow is unaffected, because AshAuthentication.AddOn.Confirmation.Actions.confirm/3 resolves sub to a user and targets that record.
This issue affects ash_authentication: from 0.5.0 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.
Affected versions
Hex
| Package | Vulnerable | Fixed in |
|---|---|---|
| ash_authentication | >= 0.5.0, < 4.15.0>= 5.0.0-rc.0, < 5.0.0-rc.14 |
4.15.05.0.0-rc.14 |
How to fix
Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.
ash_authentication Hex → 5.0.0-rc.14
- mix
{:ash_authentication, "~> 5.0.0-rc.14"} # then: mix deps.update ash_authentication
Severity breakdown
CVSS 4.0 0.0
CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
- Attack vector
- Network
- Attack complexity
- Low
- Attack requirements
- Present
- Privileges required
- Low
- User interaction
- None
- Confidentiality (vulnerable system)
- High
- Integrity (vulnerable system)
- High
- Availability (vulnerable system)
- None
- Confidentiality (subsequent systems)
- None
- Integrity (subsequent systems)
- None
- Availability (subsequent systems)
- None
Weakness
CWE-639: Authorization Bypass Through User-Controlled Key
The system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data.
How to prevent it
- Architecture and Design: For each and every data access, ensure that the user has sufficient privilege to access the record that is being requested.
- Architecture and Design, Implementation: Make sure that the key that is used in the lookup of a specific user's record is not controllable externally by the user or that any tampering can be detected.
- Architecture and Design: Use encryption in order to make it more difficult to guess other legitimate values of the key or associate a digital signature with the key so that the server can verify that there has been no tampering.
References
Advisories
Fixes and patches
Packages
Other links
Timeline
- Published
- Last updated by the source
- Latest EPSS score
Related advisories
| Advisory | Severity | Why it's related |
|---|---|---|
| EEF-CVE-2026-86688 Session id is not renewed on authentication in ash_authentication, allowing session fixation | Not rated yet | Also affects ash_authentication |
| EEF-CVE-2026-76949 Remember-me sign-in guard reads a session key that is never written in ash_authentication, allowing session replacement | Not rated yet | Also affects ash_authentication |
| EEF-CVE-2026-91039 dynamic_oidc identities are not namespaced by connection in ash_authentication, allowing cross-connection account takeover | Not rated yet | Also affects ash_authentication |
| EEF-CVE-2026-88952 OAuth2 sign-in attached to an existing account without an email comparison in AshAuthentication | Not rated yet | Also affects ash_authentication |
| EEF-CVE-2026-85500 `require_confirmed_with` is not enforced on the action and fails open on an unreadable attribute in AshAuthentication | Not rated yet | Also affects ash_authentication |
| EEF-CVE-2026-86533 Revoked session accepted because the session jti is never checked in AshAuthentication and AshAuthentication Phoenix | Not rated yet | Also affects ash_authentication |
| EEF-CVE-2026-81632 Single-use sign-in token placed in a redirect query string in AshAuthenticationPhoenix | Not rated yet | Also affects ash_authentication |
| EEF-CVE-2026-80218 Sign-in token minted for one resource accepted by another in AshAuthentication | Not rated yet | Also affects ash_authentication |
Credits: James Harton, Jonatan Männchen / EEF, Peter Ullrich
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